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Cornucopia of Ideas GNU/Linux, Networking, Security and more ...

SSH Two-Factor Authentication

Hi Folks! Proliferation of the Internet changes our life that almost anything demands for the Internet. Our personal information, bank accounts, Company’ secrets etc.. So, how we protect our computer systems from intruders ? As you know most common method is password authentication. But People are so inclined to use short passwords. Brute-Force methods prevails it. So, We need additional authentication information beside password. One of them is Two-Factor authentication. And it has different kind of versions.

Kick Start Questions and Answers

Q1: I configured my kickstart(ks.cfg) network configuration as static IP. But it reverts to dhcp after installiation. Why? network --bootproto static --device=eth0 --gateway 192.168.17.2 --ip 192.168.17.38 --nameserver 192.168.17.2,8.8.8.8 --netmask=255.255.255.0 --activate network --hostname vagrant.tbag.local And I said : do not forget to add device parameter in your kick start file and it has to be proper device name. If you configure wrong device name it reverts to dhcp after installiation. eth0 is wrong device name according to my device configuration.

Java Time Zone Update

Hi Folks! We may face consequences that we need to change time zone due to government regulations such as daylight saving time and other purposes. And it is inevitable. For OS side it is very easy to update system time zone. For Linux tzdata package comes for this purpose. But If we have Java applications, updating an OS tzdata package is not enough because Java has its own time zone database.

Sending an Email Using Shell

In this post I will introduce you about sending an email by using terminal, as sending an email via graphical MTA can be cumbersome.:) To send an email on shell terminal, I will use ssmtp which sends mails local computer to configured mail hub. It is not mail server such as postfix. Ssmtp package exists in epel-repo, so you need to add epel-repo, if you do not already add it. Install Epel Repo:

Find your Public IP in the terminal

There are couple of web sites that gives your public IP in simple form. You can call them via curl or wget. I wrote it down you can pick one of them. curl icanhazip.com curl ipinfo.io/ip wget -qO- http://ipecho.net/plain ; echo curl ident.me ;echo

Dynamic DNS

Hi Folks! It has been long time, I have not posted anything since December. Actually I had to do many things. I was battling upkeep of Company Servers and upgrading them. But during that time I learned many things and I would like to share with you all. In this post I will introduce you about dynamic DNS, which saves you hassle of persistently changing of your Router IP by ISP.